Add go toolchain support (#609)

* hack/install-go.sh: Prefer toolchain version

When a toolchain directive is present in go.mod, use its version
for downloading Go instead of the go directive. This directive
specifies which Go version to use for building.

Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Ram Lavi <ralavi@redhat.com>

* build: Prefer toolchain version in Dockerfile

When a toolchain directive is present in go.mod, use its version
for downloading Go instead of the go directive. This directive
specifies which Go version to use for building

Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Ram Lavi <ralavi@redhat.com>

* vendor: Add toolchain 1.25.7, keep go 1.25

This commit sets a toolchain of 1.25.7 mant for
building the project, while keeping 1.25 as the minimum
go version that should be used for it.

Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Ram Lavi <ralavi@redhat.com>

---------

Signed-off-by: Ram Lavi <ralavi@redhat.com>

Author: RamLavi

build/Dockerfile

@@ -14,7 +14,8 @@ WORKDIR /go/src/kubemacpool
 RUN dnf install -y wget && dnf clean all
 COPY go.mod .
 COPY go.sum .
-RUN GO_VERSION=$(sed -En 's/^go +(.*)$/\1/p' go.mod) && \
+RUN GO_VERSION=$(sed -En 's/^toolchain go(.*)$/\1/p' go.mod) && \
+    if [ -z "$GO_VERSION" ]; then GO_VERSION=$(sed -En 's/^go +(.*)$/\1/p' go.mod); fi && \
     wget -q https://dl.google.com/go/go${GO_VERSION}.${BUILDOS}-${BUILDARCH}.tar.gz && \
     tar -C /usr/local -xzf go${GO_VERSION}.${BUILDOS}-${BUILDARCH}.tar.gz && \
     rm go${GO_VERSION}.${BUILDOS}-${BUILDARCH}.tar.gz

go.mod

@@ -1,7 +1,9 @@
 module github.com/k8snetworkplumbingwg/kubemacpool
 
 // allowed_go 1.25
-go 1.25.7
+go 1.25
+
+toolchain go1.25.7
 
 require (
 	github.com/go-logr/logr v1.4.3

hack/install-go.sh

@@ -1,7 +1,10 @@
 #!/bin/bash -xe
 
 destination=$1
-version=$(grep "^go " go.mod |awk '{print $2}')
+version=$(sed -n 's/^toolchain go//p' go.mod)
+if [ -z "$version" ]; then
+    version=$(sed -n 's/^go //p' go.mod)
+fi
 arch=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/')
 tarball=go$version.linux-$arch.tar.gz
 url=https://dl.google.com/go/